The research could help find new drugs for stroke

A chemical called interleukin-10 (IL-10) appears to have a protective effect on the brain.

The US researchers say their finding may suggest a new way to minimise the damage done to the brain after a stroke, as well as possibly reducing the incidence of stroke death and improving recovery.

The period immediately after a stroke is crucial.

In around a third of patients, neurological symptoms worsen in the days following a stroke, increasing the risk of death and long-term disability.

But scientists had known little about why this happened.

Samples

Researchers from the Clinical Institute of Nervous System Diseases in Barcelona, Spain, looked at 231 hospital patients who had experienced ischemic strokes, caused by blood clots that block blood flow to the brain.

Most were admitted to hospital around eight hours after they had had a stroke. Blood samples were collected within 12 hours in 80% of patients.

Blood samples were also taken from 43 patients admitted to hospitals for non-neurological disorders.

The researchers checked the levels of two natural anti-inflammatory cytokines: IL-10 and interleukin-4 (IL-4).

It was found that patients with low levels of IL-10 in their blood during the first hours after stroke were three times more likely to have worsening neurological symptoms.

If patients had less concentrations of less than 6 picograms of IL-10 per millilitre in their blood plasma, they were likely to see a worsening of their condition within 48 hours.

Eighty-three patients saw their conditions worsen.

The researchers found no link between stroke damage with levels of IL-4.

'Reinforces evidence'

Dr Angel Chamorro, who led the research, said: "This relationship [with IL-10] was independent of other well-known predictors of clinical worsening such as clinical severity on admission, elevated glucose, early signs of tissue damage or high fever.

"Overall, this study reinforces the growing evidence that anti-inflammatory processes play a major role in human acute ischemia and suggests that IL-10 may have a potential role as a neuroprotectant in acute vascular syndromes."

But he said it was too early to say IL-10 levels should be checked as part of the standard evaluation of stroke patients.

However, he did say they those with very low IL-10 levels could be good candidates for trials of experimental drugs designed to protect brain cells.

Peter Weissberg, British Heart Foundation professor of cardiovascular medicine at the University of Cambridge, told BBC News Online: "This is one of many studies going on at the moment trying to find markers for poor outcome after strokes and heart attacks.

"It is encouraging that they have found this marker."

But he said much more research was needed.

"No two strokes are the same."